This invention relates to a method and apparatus for molding vessel hulls, and, more particularly, to a modular molding system and method employing a number of individual mold panels which are removably interconnected with one another to form a continuous negative mold surface, and then disassembled for ease of storage and re-use.
Many larger vessels including luxury yachts and sports fishing boats are constructed with a hull and other structural components including composite materials such as fiberglass. Conventionally, formation of the hull, for example, begins with the hand construction of a xe2x80x9cpositivexe2x80x9d mold or xe2x80x9cplugxe2x80x9d typically made of wood or the like. The desired contours, size and other physical aspects of the finished hull are replicated in the positive mold. The next step is to form the xe2x80x9cnegativexe2x80x9d mold, which historically has been accomplished by hand laying a first layer of fiberglass or other composite material directly onto the positive mold sometimes followed by a core layer made of various substrates which is affixed to the first fiberglass layer. Finally, a second fiberglass layer is applied by hand onto the core, or onto the first fiberglass layer if no core is employed, to form the finished negative mold. The first layer of fiberglass of the negative mold forms a continuous mold surface which matches the shape of the positive mold.
In current practice, the negative mold is formed in one section or two large half sections, i.e., a starboard half section including half of the bottom and the entire starboard side of the hull, and a port half section including the other half of the bottom and the entire port side of the hull. These half sections are connected together to form a complete negative mold, having a substantially continuous mold surface from the bow of the vessel to the stem. The hull is formed by laying up first layers of composite material directly onto the mold surface of the negative mold, followed by a core, usually made of a framework of balsa wood or foam material, and then second layers of composite material laid up on the exposed surface of the core. Once the composite material has cured, the entire hull is lifted from the negative mold by an overhead crane or the like, and moved to another site within the manufacturing facility for further construction of the vessel. The negative mold is disassembled into its two half sections, and stored for re-use.
The method and apparatus for constructing the hull of vessels described above has a number of limitations and disadvantages. One problem relates to scale. Many luxury yachts and larger sport fishing vessels are in the range of fifty to one hundred ten feet long or more. It can be appreciated that the sheer size and height of a single section, or port and starboard half sections, forming the negative mold present a number of difficulties with handling and storage. A very large facility is required to store mold section or half sections of the size noted above, and if the manufacturer builds a number of different vessel sizes and/or models, the storage and handling problems increase dramatically. In many instances, manufacturers are limited to constructing only one vessel at a time because the rest of the space in their manufacturing facility is taken up with the storage of the negative mold sections.
Another significant problem with the negative molds described above is that they cannot be utilized to construct hulls of different sizes and/or shapes. As described above, current negative molds are formed in continuous starboard and port half sections, which are interconnected at the center, thus allowing only one vessel hull to be formed therefrom. When the manufacturer desires to change the hull shape or size, e.g., width, length or height, a completely new negative mold must be constructed in accordance with the method outlined above. This is an extremely expensive and time consuming operation, and results in the formation of a new set of negative mold half sections which themselves take up valuable storage space in the facilities of the vessel manufacturer.
A further problem with the method and mold apparatus described above is related to handling of the vessel hull once it is formed. As described above, the bottom and sides of the vessel hull are formed against the mold surface of the negative mold, and allowed to cure. In order to separate the hull from the negative mold, an overhead crane or similar device must be utilized to lift the hull from the negative mold and move it to another location for further handling. This requires a manufacturing facility having comparatively high ceilings, and an expensive, heavy-duty overhead crane capable of lifting the entire hull.
It is therefore among the objectives of this invention to provide a method and apparatus for molding the hulls of vessels which substantially reduces the storage space required for the negative mold, which eliminates the need for overhead cranes to xe2x80x9cpullxe2x80x9d or transport the molded vessel hull, which allows the same negative mold to be used in the fabrication of vessel hulls of different size and shape, and, which reduces the expense of negative mold construction and storage.
These objectives are accomplished in accordance with the method of this invention, employing an apparatus which comprises a plurality of individual starboard base panels, starboard side panels, port base panels and port side panels, interconnected in a number of respective first panel groups and second panel groups, which groups are then connected end-to-end along the length of the vessel hull to be formed. The first panel groups are longitudinally spaced from one another and individually mounted on adjustable vertical supports, whereas the second panel groups are removably mounted in between adjacent first panel groups to form a continuous negative mold surface against which the vessel hull can be constructed. After the hull has been formed, the second panel groups are removed while the first panel groups remain in place, a number of trolley devices are positioned beneath the hull in the spaces vacated by the second panel groups, and then the vertical supports are operated to lower the hull onto the trolley devices at which time the first panel groups can be disassembled thus allowing the hull to be transported on the trolley devices to a location in the manufacturing facility for further construction.
One aspect of this invention is predicated upon the concept of forming a negative mold from a number of individual mold panels, instead of a single section or two large half sections as in prior molding methods and apparatus of the type described above. Each mold panel of this invention is formed on a positive mold, similar to conventional techniques, but the individual mold panels are comparatively small in size. Each mold panel is formed with a peripheral flange, and the flanges of adjacent panels abut one another when the panels are assembled. The panels are interconnected along their abutting flanges with a unique bolt assembly, described in detail below, to form the completed negative mold of this invention.
The modular nature of this invention is important in a number of respects. First, the individual mold panels are relatively small making handling and storage much less of a problem than the huge single section or half section, negative molds currently employed and described above. The individual panels can be stored off site, if desired, and therefore free up valuable space in a manufacturing facility for the construction of vessels instead of the storage of negative molds.
Secondly, the modular mold panels of this invention can be employed to fabricate vessel hulls of different size and shape. As noted above, the base of the negative mold herein includes a number of first groups of starboard and port base panels longitudinally spaced along the length of the hull to be constructed, and a number of second groups of starboard and port base panels connected between adjacent first groups. In turn, individual base panels within each group are connected to one another along their abutting flanges. In one presently preferred embodiment, the overall width of the vessel hull can be increased by placing spacers between adjacent base panels within each group, as desired. Alternatively, the side panels forming the starboard side and the port side of the mold herein may be located at one or more positions atop the base panels, i.e., at different distances from the centerline of the base section, to vary the overall width of the vessel hull. Additionally, the vessel length may be increased or decreased by changing the number of first and second groups of base panels and side panels employed.
The starboard side and port side of the negative mold of this invention are both constructed to obtain variations in the height of the sides of the vessel, and an increase or decrease in vessel length, as desired. The starboard side consists of a number of first groups of individual starboard side panels connected one on top of the other and carried by the adjustable vertical supports noted above, and a number of second groups of starboard side panels connected one on top of the other and connected between adjacent first groups of starboard side panels. The port side is similarly constructed with alternating first and second groups of port side panels, with each first group of port side panels being carried by adjustable vertical supports, and the second groups of port side panels being removably mounted between adjacent first port side panel groups. The vessel size and shape can be varied by altering the number of panels within each group, and/or changing the number of groups along the length of the negative mold.
The above-described modular construction of the starboard side and port side of the negative mold of this invention also facilitates handling of the vessel hull after it is formed. As described above, previous molding systems required the use of an overhead crane to lift the entire hull from the negative mold half sections for further handling. This step is eliminated by the method of this invention. In the presently preferred embodiment, after the vessel hull is laid up against the negative mold herein, the second groups of starboard base panels, starboard side panels, port base panels and port side panels are removed while the first groups of starboard base panels, starboard side panels, port base panels and port side panels remain in place. A number of trolley devices are then rolled into position beneath the vessel hull in the spaces vacated by the removed second panel groups. The adjustable vertical supports which carry the remaining first groups of panels are then operated to lower such first panel groups, and, hence, the vessel hull, onto the trolley devices. Once the weight of the hull is carried by the trolley devices, the remaining first groups of panels are disassembled allowing the hull to be transported on the trolley devices to any desired location within the manufacturing facility for further construction of the vessel.